Aqueous compositions of alkali metal halogenites, especially sodium chlorite, are known. Such compositions appear to function in either of two ways.
In one mode of action, the metal chlorite itself acts as an oxidant. For example, when used as an odor eliminator, the chlorite oxidizes the amines, aldehydes and thiols which are the principal components of malodorous mixtures and converts them to odorless oxidation products. In the second mode of action, the halogen dioxide, principally chlorine dioxide, performs the same function.
Halogenites such as sodium chlorite when they are a sole component in aqueous solutions at a pH of 10 or above will neutralize odors by oxidation, but only at a low rate. If the pH of the solution is lowered by acidification to a value of about 8 or less, sodium chlorite is converted to chlorine dioxide, a good oxidizer. At the lower pH values the oxidation potential of the sodium chlorite also increases. As the pH decreases further, the rate of formation of chlorine dioxide increases and a series of equilibrium mixtures between chlorine dioxide and the chlorite ion form. The overall oxidizing power of the composition increases because of the greater oxidation potential of the chlorine dioxide and because of the more reactive chlorite species.
Unfortunately, chlorine dioxide itself is offending to the olefactory senses even in trace amounts, i.e. about 5 ppm.
The art, therefore, has been faced with the problem that the reaction kinetics of aqueous compositions of alkali metal halogenites such as sodium chlorite are too slow. On the other hand, useful chlorine dioxide compositions require a low concentration of the chlorine dioxide if they are to avoid the aforementioned drawbacks.
Accordingly, it is an object of this invention to provide aqueous oxidizing compositions comprising an alkali metal halogenite with enhanced reactivity to eliminate odors rapidly but without appreciable formation of halogen oxide gases.
It is a further object of the invention to provide cleaning compositions.
It is a still further object of this invention to provide such compositions additionally containing a salt of a transition or post transition metal, or mixtures thereof.